The strongest aftershocks for two weeks hit north-western Turkey yesterday, killing one man and causing panic among traumatised survivors of last month's earthquake.

The aftershocks were centred in the city of Izmit, but they could be felt across the region. Two tremors within half an hour made the ground tremble.

Buildings shook and bits of masonry and concrete tumbled onto the streets. A number of damaged buildings collapsed, and others shifted on their precarious foundations.

"That was a bad one," said one man in Adapazari shortly after one of the tremors struck in late morning. "We don't feel very safe here."

A 30-year-old man died from head injuries in hospital after he was hit by falling debris in Izmit. More than 150 other people were injured. Some of them had jumped from balconies in terror.

Crowds of people spilled out on to the streets yesterday, and headed for any open space they could find. Children were crying, and some people fainted.

In Izmit the government-run crisis centre had to be evacuated. Yesterday's tremors were nowhere near as strong as the August 17 earthquake, but no-one was taking any chances. A tyre depot and a six-storey apartment block were among the buildings which collapsed.

In Adapazari, the local governor's office broadcast appeals for calm on loudspeakers. The authorities have urged people not to re-enter or even go near damaged buildings. Some of those hurt yesterday had been trying to retrieve valuables from their homes when the aftershocks struck.

There have been more than 1,000 additional tremors since the earthquake, and aftershocks can be expected to continue for several weeks.

It makes the task of pulling down badly damaged buildings all the more urgent. The government says that more than 70,000 buildings have been damaged. Bulldozers were hard at work in several locations yesterday, but some dangerous sites remain untouched.

More than 500,000 people have been made homeless. Officials in Ankara say they will provide 50,000 prefabricated housing units by the end of November to deal with the immediate crisis, but it will take a great deal longer to rebuild public confidence.

Parliament has given the government the power to rule by decree on matters related to the earthquake for the next three months. The cabinet met for four hours in Ankara yesterday to review relief efforts, and it continues to fend off criticism that the response of the state has been too slow and too uncoordinated.

Public anger against building contractors blamed for poor construction work in the earthquake zone has also continued to rise. Yesterday 16 developers were arrested in the town of Duzce. The justice ministry has instructed prosecutors to take rapid action against them, and others who are on the wanted list.

Reports in the Turkish media said that about 800 private law suits against allegedly corrupt contractors have already been filed by survivors in Istanbul alone.